For the third year in a row, the Aloha State gets kudos as the happiest U.S. state, with Hawaii residents scoring highest in the Gallup-Healthways Well-Being Index.

But you don't have to jet to an island for a smile, as North Dakota and Minnesota came in second and third, respectively. West Virginia's residents showed the lowest well-being scores.

Following a trend that has been consistent over the past four years, Western and Midwestern states fared well on the happiness index, accounting for nine of the slots on the top 10 happiest states' list, with Southern states sliding into half of the bottom 10 states.

The 2011 telephone survey was carried out between Jan. 2 and Dec. 29, 2011 and included a random sample of 353,492 adults, ages 18 and older, living in all 50 U.S. states and the District of Columbia. To understand state well-being, Gallup relied on six measures: life evaluation (self-evaluation about your present life situation and anticipated one in five years); emotional health; work environment (such as job satisfaction); physical health; healthy behavior; and basic access (access to health care, a doctor, a safe place to exercise and walk, and community satisfaction).

Here arethe top 10 states and their average well-being scores (out of a possible 100 points):

Hawaiians were the most likely to say they smiled or laughed a lot "yesterday," and the least likely residents to report daily worry or stress, or depression. The state also snagged the distinction of the nation's healthiest behaviors due to their good eating and exercise habits and lower smoking rates, according to Gallup.

Alaskans had the highest "life evaluation" score with the highest number of people saying they were "thriving," while residents of West Virginia were least likely to say they were "thriving;" the Mountain State also showed the highest number of obese residents, sinking the state to last place on the "physical health" index.

If you're looking for a job, that is a good job, North Dakota may be the place, as workers in the Peace Garden State reported the best work environments in the country. Delaware, meanwhile, showed the lowest job satisfaction for the third consecutive year.

Need health insurance? A move is no guarantee, but Massachusetts rose to the top spot on "basic access," partly due to the high percentage of residents with health insurance. Holding its bottom spot for a second year, Mississippi scored worst on basic necessities, which also includes having a safe place to exercise, satisfaction with your community and enough money for food, shelter and medicine.

Across the country, however, well-being remained relatively unchanged since 2008, possibly reflecting the sluggish economy, according to Gallup.

Gallup officials also note that improving the country's well-being will be a challenge, as "many states continue to face severe fiscal problems, reductions in public services, public-sector layoffs or salary cuts, and decreases in federal aid."

A study published in the December 2009 issue of the Journal of Research in Personality found that states with higher gross regional product (GRP) per capita (level of productivity and standard of living), higher income levels and higher median housing value were significantly happier than poorer areas. The study looked at Gallup's 2008 well-being scores, finding that the happiest states that year also tended to have more residents with advanced educations and jobs that were considered "super-creative," such as architecture, engineering, computer and math occupations, library positions, arts and design work, as well as entertainment, sports and media occupations.

Another study, this one published in the Dec. 17, 2009 issue of the journal Science, found that a person's self-report about their well-being matches up well with objective measures, which take into account a state's weather, home prices and other factors that are known reasons to frown (or smile).

The team used their data to statistically create a representative American. That way they could take, for example, a 38-year-old woman with a high-school diploma and making medium-wage who is living anywhere and transplant her to another state and get a rough estimate of her happiness level.

Other studies have shown being happy means being old, male and Republican. And for older couples, sex may be key, as a study reported in 2011 found that those who engaged in sexual activity were more likely to be happy with their relationship and their lives than those who had less frequent sex.

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